Grant: Discovery Grants Program - Individual

The aim of this proposal to gain insight into the underlying fluid dynamic design involved in each of the blood supply systems below, working in close collaboration with clinical researchers to ensure that the issues being addressed are pertinent. 1. Myocardial Perfusion. Vascular trees originating at the epicardium must reach highly active tissue deep within the ventricular wall in a specific pattern which is not fully understood. A pilot study in collaboration with the Mayo Clinic, in which we used a combination of micro-CT imaging and a dedicated vascular tree computer analysis program, has been successfully completed. The study was limited to vasculature on the macro scale and the aim was mainly to test the methodology. We plan now to use this methodology to study the microvasculature in a series of myocardial tissue biopsies. The subject is important for a better understanding of ischemic events within the myocardium. 2. Baroreflex Control of Blood Flow. The baroreflex mediates changes in heart rate in response to changes in blood pressure. I have an active collaboration with a neurovascular research group at Western in which I use time series analysis to examine the correlation between heart rate and blood pressure recordings. In a pilot study we showed that current theory of baroreflex function, based on an open-loop control model, is inconsistent with physiological data. Our aim is to formulate and test a closed-loop model. The subject is important in relation to the deterioration of baroreflex sensitivity with aging or disease. 3. Pulsatile Blood Flow Within the Rigid Confines of the Skull. Mechanics of this flow are not fully understood because of lack of access. Clinical focus is largely on intracranial pressure (ICP), the effects of which are still unclear. In a pilot study, in collaboration with the neurovascular group at Western, I used Fourier analysis to show that ICP is only one element in the mechanics of this flow, another is a combination of intravascular and extravascular compliance. My aim is to build an analytical model based on these early findings. The subject is important in relation to the underlying mechanics of concussion and hydrocephalus. 4. Uteroplacental Blood Flow. Blood supply to the uterus involves a group of spiral arteries which undergo dramatic transformation during pregnancy. I was invited by researchers at Washington University School of Medicine in St Louis MO for a collaborative study of the underlying fluid mechanics of this system. The results of a pilot study in which we examined the curvature and added length effects on the flow in a spiral artery has been completed. Our next step is to model the course of pregnancy whereby an increasing portion of the spiral artery is converted into an open funnel. My aim is to build a computerized model of the fluid dynamics of this spiral-funnel combination. The subject is important in relation to the failure of this blood supply system in preeclampsia.